Pathophysiology of the underactive bladder

Underactive bladder (UAB), which has been described as a symptom complex suggestive of detrusor underactivity, is usually characterized by prolonged urination time with or without a sensation of incomplete bladder emptying, usually with hesitancy, reduced sensation on filling, and slow stream often with storage symptoms. Several causes such as aging, bladder outlet obstruction, diabetes mellitus, neurologic disorders, and nervous injury to the spinal cord, cauda equine, and peripheral pelvic nerve have been assumed to be responsible for the development of UAB. Several contributing factors have been suggested in the pathophysiology of UAB, including myogenic failure, efferent and/or afferent dysfunctions, and central nervous system dysfunction. In this review article, we have described relationships between individual contributing factors and the pathophysiology of UAB based on previous reports. However, many pathophysiological uncertainties still remain, which require more investigations using appropriate animal models.

Protective Effect of a Rho-kinase Inhibitor on Bladder Dysfunction in a Rat Model of Chronic Bladder Ischemia

OBJECTIVE

To investigate the effect of fasudil, a Rho-kinase inhibitor, on chronic ischemia-related bladder dysfunction.

MATERIALS AND METHODS

Male Sprague-Dawley rats (16 weeks old) were divided into control, chronic bladder ischemia (CBI), and CBI with fasudil treatment (CBI-Fa) groups. The CBI and CBI-Fa groups underwent balloon endothelial injury of bilateral iliac arteries and received a 2% cholesterol diet for 8 weeks after the procedure to induce CBI. The CBI-Fa group was given oral fasudil (30 mg/kg/day) using zonde for 8 weeks after the procedure. The control group received a regular diet for 8 weeks. After cystometry in a conscious state, rats from each group were euthanized, and the bladders and common iliac arteries were harvested for pharmacologic and histologic examination.

RESULTS

Mean wall thickness of the common iliac arteries was significantly greater in the CBI group than in controls. Contractile responses of muscle strips were significantly lower in CBI group rats than in controls. In the CBI group, micturition interval was significantly shorter, and bladder capacity was significantly lower compared with those in controls. In the CBI-Fa group, arterial wall thickening was significantly suppressed compared with the CBI group. Significant improvements in muscle strip contractility and cystometric parameters were seen in the CBI-Fa group compared with the CBI group.

CONCLUSION

Our results suggest that chronic treatment with fasudil could prevent neointimal formation in arteries and bladder dysfunction in this rat model. Fasudil may be therapeutically useful in protecting bladder function in chronically ischemic bladders.

Can we define and characterize the aging lower urinary tract?-ICI-RS 2015

The prevalence of lower urinary tract (LUT) symptoms increases with age but the etiology is unknown. This article aims to identify research directions that clarify the basis of this association. The initial question is whether biological age is the variable of interest or a time-dependent accumulation of factors that impact on LUT function at rates that differ between individuals. In particular, the accumulation of conditions or agents due to inflammatory states or tissue ischemia is important. Much of the above has been concerned with changes to bladder function and morphology. However, the outflow tract function is also affected, in particular changes to the function of external sphincter skeletal muscle and associated sacral motor nerve control. Nocturia is a cardinal symptom of LUT dysfunction and is more prevalent with aging. Urine production is determined by diurnal changes to the production of certain hormones as well as arterial blood pressure and such diurnal rhythms are blunted in subjects with nocturia, but the causal links remain to be elucidated. Changes to the central nervous control of LUT function with age are also increasingly recognized, whether in mid-brain/brainstem regions that directly affect LUT function or in higher centers that determine psycho-social and emotional factors impinging on the LUT. In particular, the linkage between increasing white matter hyperintensities and LUT dysfunction during aging is recognized but not understood. Overall, a more rational approach is being developed to link LUT dysfunction with factors that accumulate with age, however, the precise causal pathways remain to be characterized. Neurourol. Urodynam. 36:854-858, 2017. © 2017 Wiley Periodicals, Inc.

A case series of pelvic fracture patients who developed lower urinary tract symptoms after transarterial embolization of bilateral internal iliac arteries

Cases

Transarterial embolization of bilateral internal iliac arteries (TAE) is a useful hemostatic method for the management of pelvic fracture patients, but its effects on urinary functions remain unclear. In this study, we evaluated the impact of TAE on lower urinary tract symptoms (LUTS) in 10 pelvic fracture patients.

Outcomes

Lower urinary tract symptoms before and after hospitalization were evaluated by International Prostate Symptoms Score, Overactive Bladder Symptoms Score, and Quality Of Life score. All scores showed significant worsening. The changes did not correlate with sex, age, injury severity score, or durations of unstable hemodynamics or urethral catheterization. Changes of International Prostate Symptoms Score and Quality Of Life score showed significant positive correlations with intervals between the evaluations.

Conclusion

Pelvic fracture patients treated with TAE showed significant worsening of LUTS. Risk for exacerbation of LUTS should be taken into consideration when deciding to use TAE.

Association of lower urinary tract syndrome with peripheral arterial occlusive disease

PURPOSE

To describe atherosclerosis may lead to chronic bladder ischemia, eventually resulting in lower urinary tract syndrome (LUTS), and peripheral arterial occlusive disease (PAOD). We investigated the association of LUTS with PAOD.

METHODS

This nationwide population-based cohort study was based on data from the Taiwan National Health Insurance Database from 2000 to 2010; follow-up lasted until the end of 2011. We identified patients with newly diagnosed LUTS by using International Classification of Diseases, Ninth Revision, Clinical Modification codes.

RESULTS

In total, 36,042 and 36,042 patients were enrolled in LUTS and non-LUTS cohorts, respectively. After adjustment for age, sex, and comorbidities, the risk of subsequent PAOD was 1.36-fold higher [95% confidence interval (CI) = 1.26-1.46] in the LUTS cohort than in the non-LUTS cohort. The adjusted risk of PAOD was the highest in patients with LUTS without any comorbidity [adjusted hazard ratio (aHR) = 1.93, 95% CI = 1.54-2.41]. The age-specific relative risk of PAOD was significantly higher in all age groups, particularly in those aged <49 years (aHR = 1.80, 95% CI = 1.39-2.34], in the LUTS cohort than in the non-LUTS cohort.

CONCLUSION

LUTS is a risk factor for PAOD. Physicians should consider the possibility of underlying PAOD in patients with LUTS aged <49 years and without cardiovascular comorbidities. Additional studies developing strategies for decreasing the risk of PAOD are warranted.

The link between vascular dysfunction, bladder ischemia, and aging bladder dysfunction

The vascular supply to the human bladder is derived mainly from the superior and inferior vesical arteries, the latter being directly connected to the internal iliac artery. Aging is associated with an impairment of blood vessel function and changes may occur in the vasculature at the molecular, cellular and functional level. Pelvic arterial insufficiency may play an important role in the development of bladder dysfunctions such as detrusor overactivity (DO) and the overactive bladder syndrome. Chronic ischemia-related bladder dysfunction may progress to bladder underactivity and it would be desirable to treat not only lower urinary tract symptoms (LUTS) induced by chronic ischemia, but also the progression of the morphological bladder changes. Studies in experimental models in rabbits and rats have shown that pelvic arterial insufficiency may result in significant bladder ischemia with reduced bladder wall oxygen tension. In turn, this will lead to oxidative stress associated with upregulation of oxidative stress-sensitive genes, increased muscarinic receptor activity, ultrastructural damage, and neurodegeneration. The phosphodiesterase type 5 (PDE5) inhibitor tadalafil, the α₁-adrenoceptor (AR) blocker silodosin, the β₃-AR agonist mirabegron, and the free radical scavenger melatonin, exerted a protecting effect on urodynamic parameters, and on functional and morphological changes of the bladder demonstrable in vitro. Since the agents tested are used clinically for relieving LUTS, the results from the animal models seem to have translational value, and may be of relevance for designing clinical studies to demonstrate if the drugs may prevent progression of ischemia-related functional and morphological bladder changes.

The influence of altitude hypoxia on uroflowmetry parameters in women

There is scientific evidence to suggest a correlation between hypoxia and the physiology of micturition. During a Himalayan Scientific and Mountaineering Expedition, we performed tests to investigate the functional interactions between altitude hypoxia and uroflowmetry parameters in women. The tests were carried out in seven women (36.3 ± 7.1 yr) from normoxic [1,340 meters above sea level (m a.s.l.)] to hypoxic conditions (up to 5,050 m a.s.l.) and during the return descent. The following measures were determined: uroflowmetry parameters and saturation of peripheral oxygen (SpO2). As expected, SpO2 decreased from 97.7 to 77.8% with increasing altitude. Micturition flow time, flow volume, and voiding time increased with altitude ( P < 0.04 for all), indicating a negative correlation with SpO2. In conclusion, in young adult women, micturition physiological parameters were affected during adaptation to hypoxia; the correlation with SpO2 strongly suggests a role of hypoxia in these changes. These data could help to support the design of new strategies for both prevention and medical treatment. An example of the latter might be hyperbaric oxygen therapy, which in some studies has proved able to reduce the symptoms in patients with hypoxic bladder.

Naftopidil improves locomotor activity and urinary frequency in rats with pelvic venous congestion

The α1D/A receptor antagonist, naftopidil, inhibits micturition reflex by acting on various different sites. We examined the effects of naftopidil on bladder activity and changes in the induced urinary frequency using female rats with pelvic venous congestion (PC). Twenty-four female rats were divided into sham, PC, and PC/naftopidil groups. After anesthetizing rats in the PC and PC/naftopidil groups, the bilateral common iliac veins and uterine veins were ligated. Rats in the sham and PC groups were fed a standard diet, while rats in the PC/naftopidil group were fed diets containing 0.04% naftopidil. After 4 weeks of treatment, locomotor activity, urinary nitric oxide metabolites (NOx), continuous cystometry, and plasma monoamine measurements were performed. PC rats exhibited a decrease of locomotor activity, a shorter interval between bladder contractions on continuous cystometry, and decreased urinary NOx and plasma serotonin levels than the sham rats. The PC/naftopidil rats exhibited an increase of locomotor activity, a longer interval between bladder contractions, and increased urinary NOx and plasma serotonin levels. Therefore, naftopidil might improve bladder dysfunction induced by pelvic venous congestion due to several actions in the central nervous system and bladder tissue, as well as acting as an α1 blocker to cause pelvic venous dilation.

Progressive changes in detrusor function and micturition patterns with chronic bladder ischemia

Purpose

Lower urinary tract symptoms (LUTS) are bothersome constellation of voiding symptoms in men and women as they age. Multiple factors and comorbidities are attributed to this problem but underlying mechanisms of nonobstructive nonneurogenic detrusor overactivity, detrusor underactivity and LUTS remain largely unknown. Our goal was to characterize detrusor function and voiding patterns in relation to muscarinic receptors expression, nerve fiber density, and neural ultrastructure in chronic bladder ischemia.

Materials and Methods

Iliac artery atherosclerosis and bladder ischemia were produced in male Sprague-Dawley rats. At 8 and 16 weeks after ischemia, micturition patterns and cystometrograms were recorded in conscious rats then bladder blood flow and nonvoiding spontaneous contractions were measured under general anesthesia. Bladder tissues were processed for Western blotting, immunostaining, and transmission electron microscopy.

Results

Bladder responses to ischemic insult depended on the duration of ischemia. Micturition patterns and cystometric changes at 8-week ischemia suggested detrusor overactivity, while voiding behavior and cystometrograms at 16-week ischemia implied abnormal detrusor function resembling underactivity. Upregulation of muscarinic M2 receptor was found after 8- and 16 weeks of ischemia. Downregulation of M3 and upregulation of M1 were detected at 16-week ischemia. Neural structural damage and marked neurodegeneration were found after 8 and 16 weeks of ischemia, respectively.

Conclusions

Prolonged ischemia may be a mediating variable in progression of overactive bladder to dysfunctional patterns similar to detrusor underactivity. The mechanism appears to involve differential expression of M1, M2, and M3 receptors, neural structural injury, and progressive loss of nerve fibers.

Review of the pathophysiological aspects involved in urological disease associated with metabolic syndrome

INTRODUCTION

Metabolic syndrome is a constellation of disorders that includes insulin resistance, central obesity, arterial hypertension and hyperlipidaemia. These disorders can have implications for the genitourinary apparatus.

OBJECTIVES

To conduct a review on the pathophysiological aspects that explain the relationship between metabolic syndrome and sexual dysfunction, lower urinary tract syndrome, prostate cancer and stone disease.

METHODS

We performed a qualitative, narrative literature review through a literature search on PubMed of articles published between 1997 and 2015, using the terms pathophysiology, metabolic syndrome, endothelial dysfunction, lipotoxicity, mitochondrial dysfunction, kidney stones, hypogonadism, erectile dysfunction, lower urinary tract syndrome and prostate cancer.

SYNTHESIS OF THE EVIDENCE

Metabolic syndrome constitutes an established complex of symptoms, defined as the presence of insulin resistance, central obesity, hypertension and hyperlipidaemia. Endothelial dysfunction secondary to lipotoxicity generates an inflammatory state, which involves renal cell metabolism, vascularisation of the pelvis and androgen production. These facts explain the relationship between metabolic syndrome, nephrolithiasis, lower urinary tract syndrome, hypogonadism and erectile dysfunction in men.

CONCLUSIONS

Strategies such as proper diet, regular exercise, insulin treatment, testosterone-replacement therapy, therapy with antioxidants and free-radical inhibitors and urological treatments classically used for lower urinary tract syndrome have shown promising results in this syndrome.

Association between obesity and lower urinary tract symptoms: propensity score matching study between healthy controls and obese patients seeking bariatric surgery

BACKGROUND

To date, the association between obesity and lower urinary tract symptoms (LUTS) is controversial.

OBJECTIVE

To overcome the current inconsistent results regarding the association between obesity and LUTS and to investigate the association between obesity and LUTS using propensity score matching analysis.

SETTING

Bariatric center of excellence and health promotion center at university hospital.

METHODS

From August 2012 to December 2014, a total of 260 obese patients (77 men and 180 women) visited to our bariatric center to undergo bariatric surgery. Patients' International Prostate Symptom Score (IPSS) and overactive bladder symptom score were compared with those of 844 healthy controls who had visited our health center during the same period. To control for the effects of age, 1:1 propensity score matching was used.

RESULTS

After matching propensity score forage, 73 male patients and 176 female patients were included in our study. In men, all IPSS items except "frequency" were significantly different between obese patients and controls; median scores were higher in the obese group. In women, all IPSS items except "feeling of incomplete emptying" were significantly different between the 2 groups. Both voiding and storage subscores also had marked differences in both genders (P<.001). Total IPSS, quality of life, and total overactive bladder symptom score were significantly different in both genders (P< .001).

CONCLUSION

There were marked differences in LUTS between obese and nonobese patients, including in voiding and storage symptoms. Considering the relatively young age of both groups, this case-control study supports the hypothesis of a relationship between obesity and bladder pathophysiology.

Recent advances in the understanding of male lower urinary tract symptoms (LUTS)

In this review, we have looked at three important areas in understanding male lower urinary tract symptoms. These are improvement in terminology, detrusor underactivity, and nocturia. Benign prostatic hyperplasia leading to bladder outlet obstruction has been covered in a previous review.

Effects of Omega-3 Fatty Acids on Erectile Dysfunction in a Rat Model of Atherosclerosis-induced Chronic Pelvic Ischemia

The aim of this study was to investigate whether the omega-3 fatty acids help to improve erectile function in an atherosclerosis-induced erectile dysfunction rat model. A total of 20 male Sprague-Dawley rats at age 8 weeks were divided into three groups: Control group (n = 6, untreated sham operated rats), Pathologic group (n = 7, untreated rats with chronic pelvic ischemia [CPI]), and Treatment group (n = 7, CPI rats treated with omega-3 fatty acids). For the in vivo study, electrical stimulation of the cavernosal nerve was performed and erectile function was measured in all groups. Immunohistochemical antibody staining was performed for transforming growth factor beta-1 (TGF-β1), endothelial nitric oxide synthase (eNOS), and hypoxia inducible factor 1-alpha (HIF-1α). In vivo measurement of erectile function in the Pathologic group showed significantly lower values than those in the Control group, whereas the Treatment group showed significantly improved values in comparison with those in the Pathologic group. The results of western blot analysis revealed that systemically administered omega-3 fatty acids ameliorated the cavernosal molecular environment. Our study suggests that omega-3 fatty acids improve intracavernosal pressure and have a beneficial role against pathophysiological consequences such as fibrosis or hypoxic damage on a CPI rat model, which represents a structural erectile dysfunction model.

Drug Concentration in Rat Plasma, Bladder, and Prostate After Mirodenafil Administration in a Chronic Pelvic Ischemia Model

OBJECTIVE

To evaluate the distribution of a daily phosphodiesterase type 5 inhibitor dose (mirodenafil) in rat plasma and bladder and prostate tissue in a model of atherosclerosis-induced chronic pelvic ischemia.

METHODS

Thirty-two 18-week-old male Sprague Dawley rats were divided into two groups. Group I (n = 16) comprised a chronic pelvic ischemia model treated with mirodenafil and group II (n = 16) comprised a sham-operated model also treated with mirodenafil. The mirodenafil concentrations in each organ were measured at specific time points after 14 days of daily mirodenafil administration. The drug distribution ratio of group I to group II of each organ was measured, and the bladder tissue-to-plasma and prostate tissue-to-plasma ratios were calculated.

RESULTS

The mean drug concentration in the bladder of the rats in group I did not differ significantly from that of group II after mirodenafil administration. In the prostate, the mean drug concentration of group I was significantly higher than that of group II at 1 and 4 hours after drug administration. The drug concentration was higher in the bladder tissue than in the prostate tissue and the bladder tissue-to-plasma ratio was significantly higher than the prostate tissue-to-plasma ratio.

CONCLUSION

Our results suggest that mirodenafil levels might be sufficient in the target tissue after daily treatment in an ischemia-induced aging model. Considering the difficulties of tissue distribution study in human subjects, the results of this investigation provided meaningful evidence of the application of daily doses of mirodenafil for treating lower urinary tract symptoms in an aging population.

Melatonin Improves Erectile Function in Rats With Chronic Lower Body Ischemia

INTRODUCTION

Arterial occlusive disease is the leading cause of erectile dysfunction (ED). Using an established rat model we wanted to characterize the changes caused by atherosclerosis-induced chronic ischemia on penile structures and erectile function.

AIM

To investigate the effect of melatonin on these parameters.

METHODS

Adult male Sprague-Dawley rats were divided into control, arterial injury (AI) and AI with melatonin treatment groups. AI and AI-melatonin groups underwent endothelial injury of the iliac arteries and received a 2% cholesterol diet following AI surgery for 8 weeks. AI-melatonin group rats received melatonin (20 mg/kg/day) orally for 8 weeks after AI. The control group received a regular diet. After 8 weeks, erectile function was tested. Corpus cavernosum (CC) tissues were processed for pharmacological and immunohistochemical studies, histological examination, and Western blotting.

MAIN OUTCOME MEASURES

Apomorphine test was performed to evaluate erectile function. Organ bath study was performed to measure the CC-contraction induced by KCl and phenylephrine, and relaxation induced by electrical field stimulation (EFS) and sodium nitroprusside (SNP).

RESULTS

The number of erectile responses was significantly lower in the AI group (2.5 ± 0.5/hour) than in the control (5.0 ± 0.7/hour) and in the melatonin-treated groups (5.0 ± 0.3/hour). The responses to phenylephrine were lower in the AI-groups than in the controls, but there were no differences between control and AI-melatonin groups. SNP-induced relaxation in the AI-melatonin group was higher than in the AI, but lower than in control group. The EFS-elicited relaxation responses in the AI group were significantly lower than in the control and AI-melatonin groups. Compared to controls, CC tissues from the AI group showed significantly higher collagen content, and lower protein expression of eNOS and nNOS, and increased expression of iNOS. These changes were reduced or prevented by melatonin treatment.

CONCLUSION

Treatment with melatonin reduced/prevented functional and morphological changes induced by chronic ischemia on penile structure and function.

Translational Research and Functional Changes in Voiding Function in Older Adults

Age-related LUT dysfunctions result from complex processes controlled by multiple genetic, epigenetic, and environmental factors and account for high costs of health care. This article discusses risk factors that may play a role in age-related LUT dysfunction and presents available data comparing structural and functional changes that occur with aging in the bladder of humans and animal models. A better understanding of factors and mechanisms underlying LUT symptoms in the older population may lead to therapeutic interventions to reduce these dysfunctions.

Imaging of oxygen gradients in giant umbrella cells: an ex vivo PLIM study

O2 plays a pivotal role in aerobic metabolism and regulation of cell and tissue function. Local differences and fluctuations in tissue O2 levels are well documented; however, the physiological significance of O2 microgradients, particularly at the subcellular level, remains poorly understood. Using the cell-penetrating phosphorescent O2 probe Pt-Glc and confocal fluorescence microscopy, we visualized O2 distribution in individual giant (>100-μm) umbrella cells located superficially in the urinary bladder epithelium. We optimized conditions for in vivo phosphorescent staining of the inner surface of the mouse bladder and subsequent ex vivo analysis of excised live tissue. Imaging experiments revealed significant (≤85 μM) and heterogeneous deoxygenation within respiring umbrella cells, with radial O2 gradients of up to 40 μM across the cell, or ∼0.6 μM/μm. Deeply deoxygenated (5–15 μM O2) regions were seen to correspond to the areas enriched with polarized mitochondria. Pharmacological activation of mitochondrial respiration decreased oxygenation and O2 gradients in umbrella cells, while inhibition with antimycin A dissipated the gradients and caused gradual reoxygenation of the tissue to ambient levels. Detailed three-dimensional maps of O2 distribution potentially can be used for the modeling of intracellular O2-dependent enzymatic reactions and downstream processes, such as hypoxia-inducible factor signaling. Further ex vivo and in vivo studies on intracellular and tissue O2 gradients using confocal imaging can shed light on the molecular mechanisms regulating O2-dependent (patho)physiological processes in the bladder and other tissues.

Allopurinol Protects against Ischemia/Reperfusion-Induced Injury in Rat Urinary Bladders

Bladder ischemia-reperfusion (I/R) injury results in the generation of reactive oxygen species (ROS) and markedly elevates the risk of lower urinary tract symptoms (LUTS). Allopurinol is an inhibitor of xanthine oxidase (XO) and thus can serve as an antioxidant that reduces oxidative stress. Here, a rat model was used to assess the ability of allopurinol treatment to ameliorate the deleterious effects of urinary bladder I/R injury. I/R injury reduced the in vitro contractile responses of longitudinal bladder strips, elevated XO activity in the plasma and bladder tissue, increased the bladder levels of tumor necrosis factor-α (TNF-α), c-Jun N-terminal kinase (JNK), and p38 mitogen-activated protein kinase, reduced the bladder levels of extracellular regulated kinase (ERK), and decreased and increased the bladder levels of Bcl-2 and Bax, respectively. I/R injury also elevated lipid peroxidation in the bladder. Allopurinol treatment in the I/R injury was generated significantly ameliorating all I/R-induced changes. Moreover, an in situ fluorohistological approach also showed that allopurinol reduces the generation of intracellular superoxides enlarged by I/R injury. Together, the beneficial effects of allopurinol reducing ROS production may be mediated by normalizing the activity of the ERK, JNK, and Bax/Bcl-2 pathways and by controlling TNF-α expression.

Organ-Protective Effects of Red Wine Extract, Resveratrol, in Oxidative Stress-Mediated Reperfusion Injury

Resveratrol, a polyphenol extracted from red wine, possesses potential antioxidative and anti-inflammatory effects, including the reduction of free radicals and proinflammatory mediators overproduction, the alteration of the expression of adhesion molecules, and the inhibition of neutrophil function. A growing body of evidence indicates that resveratrol plays an important role in reducing organ damage following ischemia- and hemorrhage-induced reperfusion injury. Such protective phenomenon is reported to be implicated in decreasing the formation and reaction of reactive oxygen species and pro-nflammatory cytokines, as well as the mediation of a variety of intracellular signaling pathways, including the nitric oxide synthase, nicotinamide adenine dinucleotide phosphate oxidase, deacetylase sirtuin 1, mitogen-activated protein kinase, peroxisome proliferator-activated receptor-gamma coactivator 1 alpha, hemeoxygenase-1, and estrogen receptor-related pathways. Reperfusion injury is a complex pathophysiological process that involves multiple factors and pathways. The resveratrol is an effective reactive oxygen species scavenger that exhibits an antioxidative property. In this review, the organ-protective effects of resveratrol in oxidative stress-related reperfusion injury will be discussed.

Are blood vessels a target to treat lower urinary tract dysfunction?

Bladder dysfunction is common in the general population (Stewart et al. 2010) and even more so among patients seeing a physician for any reason (Goepel et al. 2002). It often manifests as lower urinary tract symptoms (LUTS), a term originally coined to describe voiding and storage symptoms in men with benign prostatic hyperplasia (BPH) but now more universally used to describe any type of voiding and storage symptoms in both sexes. Studies into possible causes of urinary bladder dysfunction have long focused on detrusor smooth muscle cells (Turner and Brading 1999). More recently, it became clear that several other types of cells and organs contribute to regulating detrusor smooth muscle function. These include the urothelium (Andersson and McCloskey 2014; Michel 2015), afferent nerves (Michel and Igawa 2015; Yoshimura et al. 2014b), and the central and autonomic nervous systems (Fowler and Griffiths 2010; Yoshimura et al. 2014a). Alterations in any of these may at least partly be responsible for detrusor dysfunction and, accordingly, be potential targets for the treatment of bladder dysfunction. As highlighted by an article in this issue of Naunyn-Schmiedeberg's Archives of Pharmacology (Bayrak et al. 2015), there is an additional suspect, the bladder vasculature. This article will discuss the currently available experimental and clinical evidence for a role of the vasculature in causing bladder dysfunction, and how existing and emerging treatments may modulate bladder function by acting on blood vessels. Due to a similarity in concept, data on prostate perfusion will also be discussed to some extent.

Mirodenafil prevents bladder dysfunction induced by chronic bladder ischemia in rats

Purpose:

To investigate the protective effect of mirodenafil on bladder function in a rat model of chronic bladder ischemia (CBI).

Methods:

Twenty-four Sprague-Dawley rats were randomized to three groups: untreated, sham-operated rats (control group); untreated, CBI model rats (CBI group); and CBI rats treated daily with 4 mg/kg mirodenafil (CBI+mirodenafil group). The CBI and CBI+mirodenafil groups underwent endothelial injury to the iliac arteries and were fed a 2% cholesterol diet after injury. Four weeks after surgery, the CBI+mirodenafil group started daily treatment with mirodenafil for four weeks. Eight weeks after surgery, continuous in vivo cystometry and in vivo organ bath studies of detrusor muscle strips were performed.

Results:

in vivo cystometry revealed that the rats in the CBI group had a significantly higher micturition frequency, lower bladder capacity, and lower compliance than the rats in the control and CBI+mirodenafil groups. The detrusor muscle strip study showed that the magnitude of the carbachol-induced contractile response was significantly lower in the CBI group compared to either the control or CBI+mirodenafil group. Addition of daily mirodenafil after induction of CBI decreased the contractile response, compared to untreated CBI rats. CBI induced submucosal fibrosis and degenerative changes in bladder walls, which was reversed by the addition of mirodenafil.

Conclusions:

Daily treatment with mirodenafil showed protective effects against bladder dysfunction resulting from CBI in rats.

Protective effect of tadalafil on the functional and structural changes of the rat ventral prostate caused by chronic pelvic ischemia

BACKGROUND

The etiology of Benign Prostatic Hyperplasia (BPH), a common among aged men, is not fully understood, however, in addition to androgens and aging, chronic ischemia has been proposed to contribute. Using an established rat model, we investigated whether chronic ischemia alters the structural and functional properties of the ventral rat prostate, and whether phosphodiesterase type 5 (PDE5) inhibitor (tadalafil) may have a protective action.

METHODS

Adult male Sprague-Dawley rats were divided into control, arterial endothelial injury (AI), and AI with tadalafil treatment (AI-tadalafil) groups. AI and AI-tadalafil groups underwent endothelial injury of the iliac arteries and received a 2% cholesterol diet following AI. AI-tadalafil rats were treated with tadalafil (2 mg/kg/day) orally for 8 weeks after AI. The control group received a regular diet. After 8 weeks, animals were sacrificed, and pharmacological and morphological studies on prostate tissues were performed.

RESULTS

Iliac arteries from AI rats displayed neo-intimal formation and luminal occlusion, an effect that was not prevented by tadalafil treatment. In the AI group, there was an obvious epithelial atrophy and a statistically significant increase in collagen fibers compared with the controls. Immunohistochemically, there was an up-regulation of smooth muscle α-actin (SMA). Contractile responses of prostate strips to KCl, electrical field stimulation (EFS), and phenylephrine (PE) were significantly higher after AI than in controls. Chronic treatment with tadalafil prevented the increase in contractile responses in ischemic tissue, and decreased the collagen deposition compared with the AI group.

CONCLUSIONS

In this rat model, chronic pelvic ischemia caused distinct functional and morphological changes in the prostate. Prostatic tissue from ischemic animals showed an increased contractile response to electrical and pharmacological stimulation, an increase in SMA, and an increased deposition of collagen. All these changes could be prevented by treatment with the PDE5 inhibitor, tadalafil, suggesting an involvement of cyclic guanosine monophosphate (cGMP).

Prostatic inflammation induces urinary frequency in adult mice

Lower urinary tract symptoms (LUTS) including urinary frequency and nocturia are common in aging men. Recent studies have revealed a strong association of prostatic inflammation with LUTS. We developed an animal model of bacterial induced, isolated prostatic inflammation and examined the effect of prostatic inflammation on voiding behavior in adult C57BL/6J mice. Prostatic inflammation was induced by transurethral inoculation of uropathogenic E. coli—1677. Bacterial cystitis was prevented by continuous administration of nitrofurantoin. Hematoxylin and eosin (H&E) staining and bacterial culture were preformed to validate our animal model. Voiding behavior was examined by metabolic cage testing on post-instillation day 1 (PID 1), PID 4, PID 7 and PID 14 and both voiding frequency and volume per void were determined. Mice with prostatic inflammation showed significantly increased voiding frequency at PID 1, 7 and 14, and decreased volume per void at all time points, as compared to mice instilled with saline and receiving nitrofurantoin (NTF). Linked analysis of voiding frequency and voided volumes revealed an overwhelming preponderance of high frequency, low volume voiding in mice with prostatic inflammation. These observations suggest that prostatic inflammation may be causal for symptoms of urinary frequency and nocturia.

Chronic Pelvic Ischemia: Contribution to the Pathogenesis of Lower Urinary Tract Symptoms (LUTS): A New Target for Pharmacological Treatment?

The incidence of lower urinary tract symptoms, including overactive bladder (OAB), is continuing to rise, and is associated with a negative impact on quality of life and a heavy economic burden. A major risk factor for OAB is advancing age. The etiology of OAB is multifactorial and appears to involve myogenic, neurogenic, and urotheliogenic factors. In this article, we review the strengthening preclinical evidence supporting the contribution of chronic pelvic ischemia to the pathogenesis of OAB. In animal models, chronic ischemia induced by arterial injury and a high-fat diet upregulates markers of oxidative stress and proinflammatory cytokines in the urothelium and lamina propria, and leads to increased expression of nerve growth factor. These processes result in increased afferent activity and an increased frequency of micturition, reflecting a state of bladder hyperactivity. In severe, prolonged cases, bladder overactivity may develop into underactivity. Antimuscarinic therapies are the mainstay of OAB treatment, but their usefulness is limited by modest efficacy and troublesome side-effects. Our increasing understanding of the contribution of chronic ischemia to OAB is leading toward novel therapeutic options targeting chronic pelvic ischemia and its morphological, functional, and oxidative consequences. Preclinical trials have demonstrated encouraging results with α1 -adrenoreceptor blockade, phosphodiesterase type 5 inhibition, β3 -adrenoreceptor agonism, free radical scavenging, and stem cell therapy, in preventing morphological, biochemical and functional changes induced by chronic bladder ischemia.

Does hypercholesterolemia affect the relaxation of the detrusor smooth muscle in rats? In vitro and in vivo studies

To evaluate the effects of hypercholesterolemia on the relaxation function of the urinary bladder, we examined the physiological mechanisms involved in the isoproterenol-induced relaxation in isolated detrusor strips in vitro and voiding behavior in vivo in rats. Adult male Sprague-Dawley rats were fed standard (control, N = 16) or 4 % cholesterol diet (hypercholesterolemia, N = 17) for 4 weeks. Concentration-response curves for isoproterenol-induced relaxations in carbachol-precontracted detrusor muscle strips were recorded. The contributions of β2- and β3-adrenoceptors and ATP-dependent and Ca(2+)-dependent potassium channels to the relaxation response were investigated by using selective adrenergic agonists salbutamol and BRL 37344 and specific potassium channel inhibitors glibenclamide and charybdotoxin, respectively. Cystometrography was performed to assess bladder function. Hypercholesterolemic rats had higher serum cholesterol and low- and high-density lipoprotein levels than the controls with no sign of atherosclerosis. Isoproterenol-induced relaxation was significantly enhanced in the hypercholesterolemia group. Preincubation with the M2 receptor antagonist attenuated the relaxation response in both groups. The relaxation responses to isoproterenol and salbutamol were similar in both groups, while BRL 37344 appeared to produce a greater relaxant effect in the hypercholesterolemic rats. Also, the inhibitory effects of potassium channel inhibitors on relaxation responses were comparable among the groups. The cystometric findings revealed that threshold and basal pressure values were higher in the hypercholesterolemia group compared with controls. We showed that hypercholesterolemia leads to greater relaxation responses to isoproterenol, appears to impair the braking function of M2 cholinergic receptors on adrenoceptor-induced relaxations in the isolated detrusor muscle, and affects the voiding function in rats.

Detrusor Underactivity: The Current Concept of the Pathophysiology

Based on evidence from available literature, we review the pathophysiology of detrusor underactivity (DU). DU is likely to be multifactorial. Aging reduces detrusor activity, but other concomitant causes may aggravate this condition, resulting in decrease of detrusor contractility. Impaired detrusor contractility has been regarded as a major etiologic factor of DU. However, a more complex pathology has been proposed. As contributing factors to DU, we discuss disturbances of the sensory afferent side of the micturition reflex, the central nervous system (CNS) and the efferent side of the reflex, including nerves and the detrusor muscle. Particularly, dysfunction of afferent nerves in the bladder and urethra may play a crucial role in the pathogenesis of DU. In addition, recent studies suggest that chronic bladder ischemia and resultant oxidative stress cause detrusor overactivity progressing to DU and inability to empty the bladder.

Pharmacological treatment of chronic pelvic ischemia

Epidemiological studies have shown that lower urinary tract symptoms, including overactive bladder, commonly occur in both men and women, with an age-related increase in both sexes. Vascular endothelial dysfunction and urological symptoms are common in the metabolic syndrome; they also occur during the human ageing process and are independent risk factors for the development of atherosclerosis and hypertension. Pelvic arterial insufficiency may lead to impaired lower urinary tract perfusion and play an important role in the development of bladder dysfunction such as detrusor overactivity and overactive bladder. It seems reasonable, but has not been definitely established clinically, that chronic ischemia-related bladder dysfunction will progress to bladder underactivity. Studies in experimental models in rabbits and rats have shown that pelvic arterial insufficiency may result in significant bladder ischemia with reduced bladder wall oxygen tension, oxidative stress, increased muscarinic receptor activity, ultrastructural damage, and neurodegeneration. Several types of drug may be able to prevent some of these changes. Even if the α1-adrenoceptor blocker, silodosin, the phosphodiesterase type 5 inhibitor, tadalafil, the β3-α1-adrenoceptor agonist, mirabegron, and the free radical scavenger, melatonin, were unable to prevent the development of neointimal hyperplasia and consequent luminal occlusion in animal models, they all exerted a protecting effect on urodynamic parameters, and on the functional and morphological changes of the bladder demonstrable in vitro. The different mechanisms of action of the drugs suggest that many factors are involved in the pathogenesis of chronic ischemia-induced bladder dysfunction and can be targets for intervention. Since several of the agents tested are used clinically and effectively for relieving lower urinary tract symptoms, the results from animal models of chronic bladder ischemia seem to have translational value. Animal models may be of relevance for designing clinical studies to demonstrate if a certain drug may prevent progression of ischemia-related functional and morphological bladder changes.

The impact of abdominal aortic calcification and visceral fat obesity on lower urinary tract symptoms in patients with benign prostatic hyperplasia

OBJECTIVES

To investigate the impact of abdominal aortic calcification and visceral fat area (VFA) on lower urinary tract symptoms (LUTS) and clinical parameters in patients with benign prostatic hyperplasia (BPH).

METHODS

We retrospectively studied 250 patients with LUTS associated with BPH. Each participant was examined with routine examination including measurement of various data; (1) voided volume (VV), maximum urinary flow rate on free uroflowmetry, (2) postvoid residual urine volume and prostate volume using transabdominal ultrasound, (3) International Prostate Symptom Score (IPSS) and Overactive Bladder Symptom Score (OABSS), and (4) aortic calcification index (ACI) and VFA were measured by abdominal CT.

RESULTS

Mean age of the patients was 72.4 ± 9.6 years. ACI significantly correlated with VV (P = 0.0392) and tended to correlate with maximum urinary flow rate, while ACI did not correlate with subjective symptoms. VFA significantly correlated with nocturia score of IPSS (P = 0.0177) and frequency score of OABSS (P = 0.0166) and tended to correlate with urgency score of IPSS and maximum urinary flow rate.

CONCLUSIONS

Aortic calcification index (ACI) correlated with only objective parameters, while VFA correlated with only storage symptoms. This study suggested that abdominal aortic calcification and VFA have certain influence on LUTS and clinical parameters in patients with BPH.

Detrusor underactivity: Pathophysiological considerations, models and proposals for future research. ICI-RS 2013

AIMS

Detrusor underactivity, resulting in either prolonged or inefficient voiding, is a common clinical problem for which treatment options are currently limited. The aim of this report is to summarize current understanding of the clinical observation and its underlying pathophysiological entities.

METHODS

This report results from presentations and subsequent discussion at the International Consultation on Incontinence Research Society (ICI-RS) in Bristol, 2013.

RESULTS AND CONCLUSIONS

The recommendations made by the ICI-RS panel include: Development of study tools based on a system's pathophysiological approach, correlation of in vitro and in vivo data in experimental animals and humans, and development of more comprehensive translational animal models. In addition, there is a need for longitudinal patient data to define risk groups and for the development of screening tools. In the near-future these recommendations should lead to a better understanding of detrusor underactivity and its pathophysiological background. Neurourol. Urodynam. 33:591-596, 2014. © 2014 Wiley Periodicals, Inc.

Effects of chronic treatment with cilostazol, a phosphodiesterase 3 inhibitor, on female rat bladder in a partial bladder outlet obstruction model

OBJECTIVE

To investigate whether bladder dysfunction after bladder outlet obstruction (BOO) could be altered by treatment with cilostazol, a phosphodiesterase 3 inhibitor (PDE3i).

METHODS

Twelve-week-old female Sprague-Dawley rats were divided into 5 groups: groups 1 and 2, sham-operated rats and groups 3-5, BOO rats. Group 1 and 3 rats were given normal diet, group 2 and 5 rats were given high-dose PDE3i diet, and group 4 rats were given low-dose PDE3i diet. PDE3i was given within diet from the day of surgery. Four weeks after BOO, the bladder was excised and dissected into 4 longitudinal strips for isometric organ-bath assay. Contractile responses of bladder strips to electrical field stimulation (EFS), carbachol, and potassium chloride (KCl) were determined for each group.

RESULTS

BOO induced a significant increase in bladder weight in groups 3-5 compared with groups 1 and 2. PDE3i treatment did not affect bladder weight in sham or BOO rats. Contractile forces in response to EFS, carbachol, and KCl in group 3 were about 20%-40% of those in group 1. Contractile responses to EFS or KCl in PDE3i-treated BOO rats were not significantly different from those in group 3. Only high dose of PDE3i treatment in BOO rats caused a statistically significant increase in the response to carbachol compared with group 3.

CONCLUSION

PDE3i has a small but significant protective effect on the contractile dysfunction induced by a 4-week BOO in rats, although the increase in bladder mass was not altered. PDE3i could be a useful protection against contractile dysfunction of the obstructed bladder.

Urinary bladder mucosal responses to ischemia

PURPOSE

The objectives of this study were to examine the expression of various cellular proteins within the urothelium (UT) and lamina propria (LP) following chronic bladder ischemia in the rat urinary bladder.

MATERIALS AND METHODS

Urinary bladders were removed from adult Sprague-Dawley rats 8 weeks after creation of bladder ischemia and from sham controls. Immunocytochemistry was used to examine distribution of LP-vimentin-immunoreactive (IR) cells and connexins (Cx26; Cx43), and western immunoblotting or ELISA for proteins involved in UT barrier and sensory functions.

RESULTS

Ischemia was associated with a significant increase in LP-vimentin-IR cells and increased expression of the gap junction proteins Cx26 and Cx43 within the bladder UT as compared to sham control. Ischemia also resulted in an increased (p < 0.05) expression level of the junctional marker (ZO-1) and non-significantly increased expressions of the trophic factor nerve growth factor as well as norepinephrine.

CONCLUSIONS

Our findings reveal that chronic ischemia alters a number of proteins within the UT and underlying LP. These proteins are involved in barrier function, remodeling, repair as well as intercellular communication. The increased expression of LP-vimentin-IR cells suggests that changes in cell-cell interactions could play a role in ischemia-induced changes in bladder activity.

Functional consequences of chronic bladder ischemia

The pathophysiology of lower urinary tract symptoms (LUTS), particularly in the elderly, seems to be multifactorial. One of the factors involved may be chronic ischemia of the bladder caused by bladder outflow obstruction (male) or atherosclerosis (male/female). The mechanisms by which chronic ischemia initiates and causes LUTS and progressive bladder dysfunction, and the time course of the effects, are incompletely known. Bladder ischemia and repeated ischemia/reperfusion during a micturition cycle may produce oxidative stress, leading to denervation of the bladder and the expression of tissue damaging molecules in the bladder wall. This may be responsible for the development of detrusor overactivity progressing to detrusor underactivity and inability to empty the bladder. The extent of bladder dysfunction in chronic bladder ischemia may depend on the degree and duration of ischemia. To prevent chronic bladder ischemia caused by atherosclerosis and to treat its consequences, more pathophysiological knowledge is needed. Several animal models of atherosclerosis-induced chronic bladder ischemia are available and should be useful tools for further research.

Progressive vascular damage may lead to bladder underactivity in rats

PURPOSE

We assessed whether progressive vascular damage causes bladder underactivity in rats.

MATERIALS AND METHODS

Adult male Sprague Dawley® rats were divided into 4 groups. Controls received a regular diet and tap water. The L-NAME group received a 2% cholesterol diet and L-NAME (3 mg/ml) dissolved in drinking water. The arterial injury group underwent balloon endothelial injury of the common iliac arteries and received a 2% cholesterol diet and tap water after injury. The arterial injury/L-NAME group also received L-NAME dissolved in drinking water. At 8 weeks urodynamics were performed, bladder tissue was harvested for pharmacological studies, and the iliac arteries and bladders were histologically examined.

RESULTS

Iliac arteries from the injury and injury/L-NAME groups showed neointimal formation and luminal occlusion but arteries from the L-NAME group did not. In the L-NAME and injury groups bladder capacity and voided volume were less than in controls. Conversely, in the injury/L-NAME group these cystometric parameters were significantly greater than in the other groups. Post-void residual volume in the injury/L-NAME group tended to increase compared with the other groups. Contractile responses of bladder strips to various stimuli in the L-NAME, injury and injury/L-NAME groups were significantly less than in controls and the lowest in the injury/L-NAME group. The injury and injury/L-NAME groups showed a significantly increased percent of collagen compared to controls.

CONCLUSIONS

Pelvic arterial occlusive disease plus vascular endothelial dysfunction may cause progressive vascular damage resulting in bladder dysfunction that develops from bladder hyperactivity to bladder underactivity.

Adhesion molecules of detrusor muscle cells are influenced by a hypercholesterolemic diet or bladder outlet obstruction in a Wistar rat model

Background

Cell adhesion molecules (CAMs) are essential for maintaining tissue integrity by regulating intercellular and cell to extracellular matrix interactions. Cadherins and catenins are CAMs that are located on the cell membrane and are important for adherens junction (AJ) function. This study aims to verify if hypercholesterolemic diet (HCD) or bladder outlet obstruction (BOO) promotes structural bladder wall modifications specific to alterations in the expression of cadherins and catenins in detrusor muscle cells.

Methods

Forty-five 4-week-old female Wistar rats were divided into the following three groups: group 1 was a control group that was fed a normal diet (ND); group 2 was the BOO model and was fed a ND; and group 3 was a control group that was fed a HCD (1.25% cholesterol). Initially, serum cholesterol, LDL cholesterol and body weight were determined. Four weeks later, groups 1 and 3 underwent a sham operation; whereas group 2 underwent a partial BOO procedure that included a suture tied around the urethra. Six weeks later, all rats had their bladders removed, and previous exams were repeated. The expression levels of N-, P-, and E-cadherin, cadherin-11 and alpha-, beta- and gamma-catenins were evaluated by immunohistochemistry with a semiquantitative analysis.

Results

Wistar rats fed a HCD (group 3) exhibited a significant increase in LDL cholesterol levels (p=0.041) and body weight (p=0.017) when compared to both groups that were fed a normal diet in a ten-week period. We found higher β- and γ-catenin expression in groups 2 and 3 when compared to group 1 (p = 0.042 and p = 0.044, respectively). We also observed Cadherin-11 overexpression in group 3 when compared to groups 1 and 2 (p = 0.002).

Conclusions

A HCD in Wistar rats promoted, in addition to higher body weight gain and increased serum LDL cholesterol levels, overexpression of β- and γ-catenin in the detrusor muscle cells. Similar finding was observed in the BOO group. Higher Cadherin-11 expression was observed only in the HCD-treated rats. These findings may be associated with bladder dysfunctions that occur under such situations.

Protective effect of a β3-adrenoceptor agonist on bladder function in a rat model of chronic bladder ischemia

BACKGROUND

The β3-adrenoceptor (AR) agonist mirabegron has been introduced as a treatment for the overactive bladder. Its effects on the function of the ischemic bladder are not known.

OBJECTIVE

To investigate the effect of mirabegron in a rat model of chronic ischemia-related bladder dysfunction.

DESIGN, SETTING, AND PARTICIPANTS

Male Sprague-Dawley rats were divided into three groups: control (n=10), arterial endothelial injury (AI; n=16), and AI with mirabegron treatment (AI-mirabegron; n=10). AI and AI-mirabegron groups underwent endothelial injury of the iliac arteries and received a 2% cholesterol diet following AI. AI-mirabegron rats received mirabegron (10mg/kg/d) orally for 8 wk. The control group received a regular diet.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

After 8 wk, urodynamic investigation was performed in awake animals. Pharmacologic in vitro studies and histologic examination of the iliac arteries and bladders were performed.

RESULTS AND LIMITATIONS

Iliac arteries from both AI and AI-mirabegron rats displayed neointimal formation and luminal occlusion. Micturition interval (MI), bladder capacity (Bcap), and voided volume (VV) in the AI group were significantly less than in the control group (p<0.01). In the AI-mirabegron group, MI, Bcap, and VV were significantly larger than in the AI group (p<0.05) but significantly less than in the control group (p<0.05). Contractile responses of bladder strips to potassium chloride, electrical field stimulation, and carbachol were significantly lower after AI than in controls; responses in preparations from AI-mirabegron-treated animals were similar to those of controls. The AI group showed a significantly higher percentage of collagen (28.6 ± 1.57%) compared with the controls (8.65 ± 0.67%) and AI-mirabegron-treated animals (17.2 ± 2.32%). The mirabegron dose used in this study may potentially limit the translational value of the results.

CONCLUSIONS

In the chronically ischemic rat bladder, treatment with mirabegron seems to protect bladder function and morphology, resulting in reduced bladder hyperactivity. If the results are valid for humans, they support β3-AR agonism as a potential treatment of chronic ischemia-related bladder dysfunction.

Effects of silodosin, a selective α1A-adrenoceptor antagonist, on bladder blood flow and bladder function in a rat model of atherosclerosis induced chronic bladder ischemia without bladder outlet obstruction

PURPOSE

We investigated the effects of the selective α1A-adrenoceptor antagonist silodosin on bladder blood flow and bladder function in a rat model of atherosclerosis induced chronic bladder ischemia without bladder outlet obstruction.

MATERIALS AND METHODS

The chronic bladder ischemia model was prepared by creating balloon endothelial injury of the bilateral iliac arteries in male rats. Using an osmotic pump, chronic bladder ischemia rats received silodosin subcutaneously at a rate of 0.1 or 0.3 mg/kg per day, or vehicle for 8 weeks. All groups received a 2% cholesterol diet throughout the experiment. For each α1-adrenoceptor subtype mRNA expression in bladder microvessels was examined by in situ hybridization. Bladder blood flow was measured using a laser speckle blood flow imager. Malondialdehyde in bladder tissue and 8-hydroxy-2'-deoxyguanosine in urine were measured as markers of oxidative stress. A metabolic cage study and cystometry were performed in conscious rats.

RESULTS

The expression of all α1-adrenoceptor subtype mRNA was observed in rat bladder microvessels. Silodosin abrogated the decreased bladder blood flow in the empty bladder and during bladder distention that were evident in rats with chronic bladder ischemia. Levels of oxidative stress markers in these rats were significantly decreased by silodosin administration. Silodosin ameliorated bladder dysfunction in rats with chronic bladder ischemia in the metabolic cage study and on cystometry.

CONCLUSIONS

Results suggest that in ischemic conditions α1-adrenoceptor antagonists such as silodosin may improve bladder function by restoring bladder blood flow.

Impaired detrusor contractility in a rat model of chronic bladder ischemia

OBJECTIVE

To examine the effect of chronic ischemia associated with vascular disorders on bladder function, we investigated bladder contractility and changes in morphology and nerve distribution in a rat model of chronic bladder ischemia.

METHODS

Adult male Sprague-Dawley rats were divided into arterial endothelial injury, sham, and control groups. The injury group underwent balloon endothelial injury of the iliac arteries and received a 2% cholesterol diet. The sham group was only incised bilaterally in the inguinal region and received the 2% cholesterol diet. The control group did not undergo any procedure and received a regular diet (0.09% cholesterol). All animals were euthanized after 8 weeks. Bladders were removed and weighed, and sections were used for muscle strip contraction and histologic analyses. Cross-sections of dissected common iliac arteries were examined histologically.

RESULTS

Bladder contractile response and tension were significantly decreased in the injury group compared with the sham and control groups. Tissue from the injury group exhibited marked arterial occlusion with wall thickening. In the injury group, the collagen and muscle ratio (0.80 ± 0.12) was significantly greater than in the control (P = .01) and sham (P = .04) groups. Significantly fewer protein gene product 9.5 (PGP9.5)-positive nerve fibers were found in the injury group (513 ± 53) than in the control (P = .01) and sham (P = .03) groups.

CONCLUSION

Vascular occlusive disorders cause fibrosis and reduce the number of nerves innervating the bladder, which leads to decreased bladder contractility in a rat model of chronic bladder ischemia.

Effect of melatonin on chronic bladder-ischaemia-associated changes in rat bladder function

WHAT'S KNOWN ON THE SUBJECT? AND WHAT DOES THE STUDY ADD?: There are many studies showing melatonin's potent endogenous free radical scavenging and antioxidative properties, which protect against oxidative insult, but there is no information about the effect of chronic treatment with melatonin on oxidative-stress-related bladder dysfunction caused by chronic ischaemia. The model used in this study shows that functional and morphological changes caused by chronic bladder ischaemia and oxidative stress were protected by chronic treatment with melatonin, resulting in improvement of bladder hyperactivity.

OBJECTIVE

To investigate the potential therapeutic benefit of melatonin for chronic ischaemia-related bladder dysfunction.

MATERIALS AND METHODS

Adult male Sprague-Dawley rats were divided into control, arterial injury (AI), AI with low-dose melatonin treatment (AI-ML) and AI with high-dose melatonin treatment (AI-MH) groups. The AI, AI-ML and AI-MH groups underwent a procedure to induce endothelial injury of the iliac arteries and received a 2% cholesterol diet after AI. The rats in the AI-ML and AI-MH groups were treated with melatonin 2.5 or 20 mg/kg/day orally for 8 weeks after AI. The control group received a regular diet. After 8 weeks, urodynamic investigations were performed. Bladder tissues and iliac arteries were processed for pharmacological studies, and for immunohistochemical and histological examination.

RESULTS

Iliac arteries from AI, AI-ML and AI-MH rats displayed neo-intimal formation and luminal occlusion. In the AI group, the micturition interval was significantly shorter, and bladder capacity and voided volume were lower than in the controls. Contractile responses of bladder strips to KCl, electrical field stimulation and carbachol were significantly lower after AI than in the controls. The AI bladders were found to have a significantly increased collagen ratio, oxidative stress and inducible nitric oxide synthase (NOS) expression, and decreased constitutive NOS expression compared with the controls. In the AI-ML and AI-MH groups, neo-intimal formation was not prevented, but there were beneficial effects on bladder function and morphology. In the AI-ML group, the beneficial effects failed to reach statistical significance. In the AI-MH group, melatonin significantly improved oxidative stress and NOS expression, and there were significant improvements in all the functional and morphological variables compared with the AI group.

CONCLUSIONS

Arterial occlusive disease may lead to chronic bladder ischaemia and bladder hyperactivity associated with oxidative stress. In the model used, chronic treatment with melatonin protected bladder function and morphology, probably through its free radical scavenging and antioxidative properties. Melatonin may prevent oxidative damage and improve ischaemia-related bladder dysfunction.

Effects of coenzyme Q10 on bladder dysfunction induced by chronic bladder ischemia in a rat model

PURPOSE

We investigated the protective effects of coenzyme Q10 on bladder dysfunction in a rat model of atherosclerosis induced chronic bladder ischemia.

MATERIALS AND METHODS

A total of 24 male Sprague-Dawley® rats at age 16 weeks were divided into 4 groups of 6 each, including group 1--untreated, sham operated rats, group 2--coenzyme Q10 treated, sham operated rats, group 3--untreated rats with chronic bladder ischemia and group 4--coenzyme Q10 treated rats with chronic bladder ischemia. Groups 3 and 4 received an endothelial injury to the iliac arteries and were fed a 2% cholesterol diet for 8 weeks. Groups 2 and 4 were treated with coenzyme Q10 and the others were treated with vehicle for 4 weeks. Eight weeks postoperatively we performed continuous in vivo cystometry, an in vitro detrusor muscle strip study and a malondialdehyde assay. Histological examination of the bladder walls and iliac arteries was also done.

RESULTS

In vivo cystometry revealed that coenzyme Q10 administration after the induction of chronic bladder ischemia prolonged micturition frequency and the intercontraction interval, and increased bladder capacity compared to those in untreated rats with chronic bladder ischemia. In the detrusor muscle strip study coenzyme Q10 administration after the induction of chronic bladder ischemia increased contractile responses compared to those in untreated rats with chronic bladder ischemia. Rats with chronic bladder ischemia also showed higher malondialdehyde in bladder tissue and serum than the other groups. Chronic bladder ischemia induced submucosal fibrosis of the bladder walls and a degenerative change in the blood vessel tunical media, as shown on histological examination.

CONCLUSIONS

Our study suggests that coenzyme Q10 acts as an antioxidant to protect bladder function in this chronic bladder ischemia model.

Latest treatment for lower urinary tract dysfunction: therapeutic agents and mechanism of action

Recent studies suggest that antimuscarinics might suppress bladder afferent activity by blocking muscarinic receptors in the urothelium, myofibroblasts and detrusor, thereby improving overactive bladder symptoms. β(3)-Adrenoceptors are predominantly expressed in the human bladder and mediate relaxation of detrusor muscle. β(3)-Adrenoceptor agonists increase bladder capacity and prolong micturition interval. It is assumed that β(3)-adrenoceptor agonists could exert an inhibitory effect on bladder afferent through β(3)-adrenoceptors in the urothelium and detrusor, which eventually improve the symptom of urgency. Mirabegron is a potent and selective β(3)-adrenoceptor agonist. A Japanese phase 3 study showed that mirabegron has excellent efficacy and safety for treating overactive bladder. α(1)-Adrenoceptor antagonists (α(1)-blockers) have become a mainstay of male lower urinary tract symptoms treatment. The α(1)(A) subtype is known to mediate functional obstruction as a result of benign prostatic enlargement. Recent studies have suggested that α(1)(A)-adrenoceptors are additionally involved in the generation of storage symptoms. The α(1)(D) subtype is thought to play a role in the facilitation of voiding reflex; that is; storage symptoms. α(1)-Blockers often fail to alleviate overactive bladder symptoms. In this context, combination therapy with α(1)-blockers and antimuscarinics has been recommended. Treatment with 5α-reductase inhibitor for 1 year improves urinary symptoms and flow rate by reducing prostatic volume in men with benign prostatic enlargement. A pooled analysis showed that the long-term (2 or 4 years) treatment with 5α-reductase inhibitor reduced the rate of progression to acute urinary retention and surgery. Combination therapy with 5α-reductase inhibitor and α(1)-blocker was shown to provide a rapid improvement in lower urinary tract symptoms, and reduce the relative risk of acute urinary retention and benign prostatic hyperplasia-related surgery. Phosphodiesterase inhibitors might target a nitric oxide-cyclic guanosine monophosphate pathway in the prostate, urethra and bladder. Phosphodiesterase-5 inhibitors (sildenafil or tadalafil) were shown to provide clinically relevant improvements in both male lower urinary tract symptoms and erectile dysfunction.